Peatlands characteristically accumulate organic matter due to low decomposition rates, but peatland disturbance alters local physicochemical conditions often resulting in loss of soil organic matter and emission of CO₂. Restoration may reduce peat oxidation, but traditional measurements of decomposition are time-consuming. The Tea Bag Index (TBI) is a simple, standardized method to measure decomposition rates in soils. We used the TBI to measure decomposition rate at four restored peatland sites across Canada that were used for peat extraction or disturbed by oil extraction (former well-sites), comparing to undisturbed and unrestored sites. We measured environmental conditions including soil temperature, water table position and peat pH from May to August 2016. Litter bags were buried for one year alongside tea bags at one site for a direct comparison of decomposition rates between the methods. There were no significant differences for TBI decay constant (k_TBI) between treatments of restored, unrestored or undisturbed sites across the whole data set, but some differences were found among treatments within the same peatland site for sections restored at different times in the past. Soil temperature, pH, and water table were not significantly related to k_TBI, but were negatively correlated with the stabilization factor (S). The k_TBI and litter bag k were significantly different but positively correlated. The TBI is not easily comparable to traditional litter bags, but is less costly in both time and money, and may be used in conjunction with additional parameters to determine decomposition patterns with potential for use as a metric for evaluating restoration outcomes.

As fen peatlands have been heavily disturbed by resource extraction in northeastern Alberta, Canada, fen construction has been completed. In order to optimize biogeochemical function of future constructed fens, it is beneficial to understand methane (CH₄) cycling of newly constructed fens, and how revegetation strategies influence CH₄ dynamics. Here, we investigate the effects of two vascular species used for fen construction on CH₄ dynamics. A factorial greenhouse experiment using peat columns and a laboratory incubation experiment were used to understand differences in CH₄ production, emissions, pore water concentration, and oxidation between Carex aquatilis Wahlenb. and Juncus balticus Willd. The experiment also considered how water sourced from the constructed fen influenced CH₄ dynamics compared to natural rich fen water. Higher pore water CH₄ concentration and potential CH₄ production were found at C. aquatilis columns, possibly associated with higher labile carbon throughout the column. In columns with J. balticus, evidence to support radial oxygen loss reducing CH₄ concentration and production was found. Water sampled from peat columns with constructed fen water had higher Fe (all cation forms), Mn (all cation forms), SO₄²−, and NO₃− compared to columns with rich fen water, which corresponded to lower CH₄ emissions and pore water concentration. Results from this study could be used to inform revegetation designs of future constructed fens that consider greenhouse gas emissions, including CH₄, as a reclamation goal.

Aims: This study assesses the relative effects of hydrology and colonization by vascular plants on belowground C and N mobilization, and emission of CO2 and CH4 in an extracted bog under restoration in Alberta (Canada). Methods: A wet (high water table) and dry (low water table) area were identified at the site and plots with cottongrass (Eriophorum vaginatum) or bare peat were established in each area. Plant growth, peat and porewater dissolved C (DOC) and N (TDN), microbial biomass and the emissions of CO2 and CH4 were monitored at the plots throughout the growing season. Results: The largest concentrations of DOC were measured in dry and bare sites. Lower E2:E3 ratios suggested a higher aromaticity of the DOC at these sites that were net sources of CO2 and CH4. The concentration of TDN was greater in plots with cottongrass and high water table, supporting a more abundant microbial biomass. Cottongrass dominated plots also had larger gas emissions as compared to bare plots even though they were net C sinks due to their high photosynthetic rates. Conclusion: Maintaining a high water table is key to reducing peatland C losses. While vascular plant presence seems to prime the release of N and greenhouse gases, the inputs of C exceeded the losses and recovered the C sink function of the peatland ecosystem in the short term. Carbon inputs are maximized under high water table and plant presence.

Restoration of extracted horticultural peatlands commonly includes distribution of vegetation and propagules from nearby undisturbed sites over the recently-exposed surface. The resulting growth includes both mosses and vascular plants, which are important contributors to returning a peatland to a net carbon-storing ecosystem. Nitrous oxide (N₂O) flux has not been widely investigated in these restored ecosystems. We compared the N₂O flux from plots containing a vascular plant, Eriophorum vaginatum, to plots lacking vascular plant cover at a recently restored peatland. We hypothesized that E. vaginatum would result in decreased N₂O emissions compared to areas with only moss or bare peat due to rapid plant uptake of peat nitrogen. After an early-summer pulse of emitted N₂O, study plots containing E. vaginatum transitioned to net consumers of N₂O while bare plots remained sources as the summer progressed. Furthermore, E. vaginatum growing in the wettest parts of the study site also had significantly more extractable nitrogen in pore water collected from 75 cm below the surface, beyond the depth of most roots. We suggest the priming effect driven by the roots of this vascular plant, combined with high water levels, frees some nitrogen from previously-inaccessible recalcitrant organic matter that then is taken up by plant roots and/or soil microorganisms, preventing its release as N₂O. Vascular plants may play important roles in both greenhouse gas processes and in the nutrient cycles of restored peatlands and these complex processes need further investigation to guide effective restoration efforts that aim to return these disturbed ecosystems to net greenhouse gas sinks.